Free Ligand Research Articles

A π‐Conjugated Porphyrin Complex as Cathode Material Allows Fast and Stable Energy Storage in Calcium Batteries

AbstractRechargeable calcium batteries (RCB) are prospective candidates for sustainable energy storage, as they hold the promise of the high energy density of lithium‐ion batteries (LIBs) while simultaneously combining it with highly abundant raw materials. However, for long time, calcium batteries have faced severe issues with regard to cycling stability, until recently developments demonstrated improved battery cycle life when employing CaSn alloy anodes with fluorinated alkoxyborate electrolytes. These findings opened up the possibility to study cathode materials for RCBs not only in a more comparable manner, but also in a practical full cell design. As representative of emerging organic electrode materials (OEMs), we investigated tetrakis(4‐pyridyl) porphyrin as both free ligand (H2TPyP) and in the form of its copper MOF complex (CuTPyP−MOF) as active cathode species in RCBs. The cells demonstrated high capacities and excellent cycling stability at the same time. Even at elevated current densities of e. g., 2000 mA/g the full cells delivered stable capacities of ~90 mAh/g proving its excellent rate capability. This study explores the electrochemical performance of porphyrin active materials in calcium batteries and represents a significant step forward in the progress toward organic electrodes for multivalent energy storage systems.

Equilibria in the aqueous system of cobalt(II) based on 2-picolinehydroxamic acid and N-(2-hydroxybenzyl)phenylalanine and its ability to inhibit the propagation of cancer cells

Mixed-ligand complexes of cobalt(II) with two bioligands, viz. 2-picolinehydroxamic acid and the reduced Schiff base N-(2-hydroxybenzyl)phenylalanine, were studied in aqueous solution by potentiometry and UV–Vis spectroscopic analysis. The coordination mode of the complexes and their stability were determined and compared to their parent species. Stacking interactions between the rings present in the ligands influence the stability of the complexes. Also, UV–Vis spectroscopy revealed that the stacking interactions affected the intercalation of DNA and mixed-ligand complexes. The in vitro anticancer activity of the free ligand 2-picolinehydroxamic acid and the complexes was tested against cervical and gastric human adenocarcinoma epithelial cell lines. At concentrations of 0.06 and 0.11 mM, the mixed-ligand structures showed the ability to reduce gastric cancer cells with no inhibitory effect on mouse fibroblasts. The cytotoxic effect was accompanied by damage to the cell nuclei, which may confirm that the complexes demonstrate effective binding to DNA. No determination of minimal inhibitory and bactericidal/fungicidal concentrations against the test organisms was possible at higher complex concentrations due to precipitation.

Synthesis, Crystal Structure Analyses, and Antibacterial Evaluation of the Cobalt(II) Complex with Sulfadiazine-Pyrazole Prodrug

The complex [Co(L)(H2O)4](NO3)2 of (E)-4-(2-(3-methyl-5-oxo-1-(pyridin-2-yl)-1H-pyrazol-4(5H)-ylidene)hydrazinyl)-N-(pyrimidin-2-yl)benzenesulfonamide (L) was synthesized via the self-assembly technique. Its molecular and supramolecular structures were analyzed using FTIR, elemental analyses, and single-crystal X-ray diffraction, as well as Hirshfeld calculations. This complex crystallized in the triclinic space group P1¯ with Z = 2. The crystallographic asymmetric unit comprised one complex cation and two nitrate counter anions. This complex had distorted octahedral geometry around the Co(II) ion. Numerous intermolecular interactions affecting the molecular packing of this complex were conformed using Hirshfeld investigations. The most significant contacts for the cationic inner sphere [Co(L)(H2O)4]2+ were O···H (38.8%), H···H (27.8%), and N···H (9.9%). On the other hand, the main interactions for the counter NO3¯ ions were the O···H (79.6 and 77.8%), O···N (8.0%), and O···C (9.1%). A high propensity for making interactions for each atom pair in the contacts O…H, N…C, N…H, and C…C was revealed by enrichment ratio values greater than 1. The antibacterial efficacy of the complex and the free ligand were assessed. The free ligand had higher antibacterial activity (MIC = 62.5–125 µg/mL) than the [Co(L)(H2O)4](NO3)2 complex (MIC ≥ 250 µg/mL) versus all the studied bacteria.

Fe(III), Ni(II), and Cu(II)-moxifloxacin-tri-substituted imidazole mixed ligand complexes: Synthesis, structural, DFT, biological, and protein-binding analysis

Herein, three new mixed-ligand complexes were synthesized through the reaction of Fe(III), Ni(II) and Cu(II) with moxifloxacin (MOX) in the presence of tri-substituted imidazole (TSI) to investigate their antibacterial, antifungal, and antioxidant potential. Elemental analysis, molar conductivity, electronic spectra, infrared spectroscopy, mass spectrometry, magnetic studies, thermal gravimetric investigations have been utilized for insuring the chelation process and structural elucidation. Results revealed that MOX and TSI interact with the metal ions via the (carbonyl oxygen and the carboxylic oxygen) and (hydroxyl oxygen and imidazole-ring nitrogen) atoms for MOX, and TSI, respectively. Octahedral geometries have been proposed for the Fe(III), Ni(II) complexes, while a distorted tetrahedral geometry was proposed for the Cu(II) complex. The proposed structures had been optimized via Density functional theory (DFT) calculations. Moreover, the frontier molecular orbitals (FMOs), in terms of HOMO and LUMO, and the molecular electrostatic potential (MEP) were obtained. Furthermore, the energy gap, chemical hardness, softness, chemical potential, electrophilicity index were evaluated. The antimicrobial potential was in vitro investigated against some common pathogenic bacterial and fungal strains; moreover, the antioxidant activity was evaluated using DPPH method. Results revealed that the three synthesized complexes had high antimicrobial activity against all tested phytopathogens and a significant antioxidant potential, compared to the free ligands. Furthermore, the in vitro potential was validated utilizing molecular docking investigation against four target receptors: 5JQ9, 6CLV, 3CKU, and 5IJT. The molecular docking results showed that Fe(III), Ni(II), and Cu(II) complexes had the highest activity towards the 5JQ9, (6CLV and the 3cku), and 5IJT receptors, respectively.

Self-Assembly of Core-Shell Hybrid Nanoparticles by Directional Crystallization of Grafted Polymers.

Nanoparticle self-assembly is an efficient bottom-up strategy for the creation of nanostructures. In a typical approach, ligands are grafted onto the surfaces of nanoparticles to improve the dispersion stability and control interparticle interactions. Ligands then remain secondary and usually are not expected to order significantly during superstructure formation. Here, we investigate how ligands can play a more decisive role in the formation of anisotropic inorganic-organic hybrid materials. We graft poly(2-iso-propyl-2-oxazoline) (PiPrOx) as a crystallizable shell onto SiO2 nanoparticles. By varying the PiPrOx grafting density, both solution stability and nanoparticle aggregation behavior can be controlled. Upon prolonged heating, anisotropic nanostructures form in conjunction with the crystallization of the ligands. Self-assembly of hybrid PiPrOx@SiO2 (shell@core) nanoparticles proceeds in two steps: First, the rapid formation of amorphous aggregates occurs via gelation, mediated by the interaction between nanoparticles through grafted polymer chains. As a second step, slow radial growth of fibers was observed via directional crystallization, governed by the incorporation of crystalline ribbons formed from free polymeric ligands in combination with crystallization of the covalently attached ligand shell. Our work reveals how crystallization-driven self-assembly of ligands can create intricate hybrid nanostructures.

Synthesis, anticancer, antibacterial, antifungal, DNA interactions, ADMET, molecular docking, and antioxidant evaluation of novel Schiff base and their Co(II), Ni(II) and Cu(II) complexes

Here, three bivalent transition metal complexes of [ML2] kind (where M = Co(II), Ni(II), Cu(II); HL = 2-(E)-(5-cyclohexyl-2-methoxyphenylimino)methyl)-5-methylphenol), and various analytical techniques such as elemental analysis, mass, IR, NMR, UV–visible, TGA, magnetic moments, and ESR were employed for characterization. From the analytical data it is found that the Ni (II) and Cu (II) complexes adopted a square planar geometry, while the Co (II) complex adopted an octahedral geometry. Molecular docking investigations were carried out of Schiff base ligand (HL), the results illustrated that the ligand exhibited significant affinities for a few proteins. Monometallic metal compounds interaction with CT-DNA was studied by fluorescence measurements, viscosity and UV–Vis investigations, which is illustrated that all the three metal compounds strongly intercalated to CT-DNA. The synthesized metal compounds (1a-1c) with supercoiled pBR322 DNA was used in cleavage experiments. Based on findings, DNA cleavage by the Cu(II) complexes was more effective than that of the Co(II) and Ni(II) compounds. All synthesised compounds toxic effects on cancer cell lines A-549 and MCF-7 were evaluated by MTT assay. The obtained results indicated that Cu(II) complex is more effective towards tumour cells than other complexes. In addition to the evaluation of all synthesised complexes for antimicrobial properties, it was observed that all of the metal complexes showed higher efficacy against microorganisms compared to the free ligand. Finally, drug likeness and ADMET studies was performed on Schiff base ligand (HL). These studies indicated that the ligand possessed high potency and showed potential as a drug agent for pathogens causing deformities.

Microwave assisted synthesis, characterization and bioactivity evaluation of a cobalt (II) complex with a novel Schiff base ligand derived from phenylacetyl urea and salicylaldehyde

The study comprehensively focusses on the synthesis and characterization of a novel Co(II) metal complex formed by the condensation of phenylacetyl urea and salicylaldehyde with Thiocyanate ion using an eco-friendly microwave irradiation technique, which resulted in a higher yield. The molecular formula and geometry of the complex were deduced through an array of techniques including UV–Vis spectra, FT-IR, Far IR, Cyclic voltammetry, thermal analysis, and Powder XRD. The molar conductance data revealed a non-electrolyte [1:0] type complex. Notably, the FT – IR spectral peaks obtained at 3388 cm−1, 2914 cm−1,1622 cm−1 shows that Schiff base and Thiocyanate ions were coordinated to the metal ion in a monodentate manner. Furthermore, electronic spectra values confirmed a pseudo tetrahedral geometry for the complex. Intriguingly, our study also encompassed an exploration of the biological activities of both the Schiff base ligand and the Co(II) metal complex. By subjecting them to antimicrobial assays against various microorganisms, including Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeurginosa, Staphlococcus aureus, Bacillus cereus, Aspergillus favus, Aspergillus niger, Aspergillus sojae, Aspergillus oryzae, and Candida albicans. It was found that the complex exhibited moderate activity against bacteria and remarkably enhanced activity against fungi when compared to the free Schiff base ligand. Additionally, we investigated the DPPH free radical scavenging activity of the complex and the ligand, unveiling that the Co(II) complex demonstrated significantly higher antioxidant activity in comparison to the ligand. These results highlight the potential of the synthesized Co(II) complex as a promising candidate for biomedical applications. Overall, this study not only sheds light on the synthesis and characterization of the Co(II) metal complex with a novel Schiff base ligand but also unravels its distinct biological activities, indicating its potential significance in antimicrobial and antioxidant applications.

Anti-carcinoma and anti -microbial behavioral studies for octahedral synthesized Schiff base metal complexes

2,2′-((1Z-1′Z) (1,3-diphenylpropane-1,3-diylidene) bis (azanylylidene)) dibenzoic acid (H2L) Schiff base ligand, derived from condensation reaction in a molar ratio 2:1 between anthranilic acid and dibenzoyl methane, respectively. Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes were obtained from 1:1 (ligand: metal salt) reaction. Elemental analyses, IR, 1H NMR, UV–Vis, ESR, mass spectra, conductivity, and magnetic susceptibility measurements as well as thermal (TG/DTG) analyses have been used to conclude the molecular structure of the prepared complexes. From the analytical and spectroscopic tools, the stoichiometry of the complexes was found to be of ML type with octahedral geometry. The conductivity values supported the electrolytic nature of Cr(III) and Fe(III) complexes and non- electrolytic nature of the remaining complexes. From IR studies, the involvement of two azomethine nitrogen atoms and two carboxylate oxygen has been proved as tetradendate binding sites of the ligand. Screening Schiff base and its complexes for their antimicrobial activity against Streptococcus pneumoniae and Bacillus subtilis as G + bacteria; Pseudomonas aeruginosa and Escherichia coli as G− bacteria) and fungi (Aspergillus fumigatus; Syncephalastrum racemosum; Geotricum candidum and Candida albicans) has been conducted by disk diffusion method. The Comparison between the antimicrobial activity of the metal complexes and the free ligand showed the advancement of the metal complexes. Unfortunately, no promising anti-tumor activity has been detected for the ligand and its metal complexes as they were evaluated against human cancer (MCF-7 cells viability).

In vitro biological activities of novel Ni(II)-2-chloroquinoline derivative complex: Synthesis, characterization and computational studies

Quinoline derivative nickel complexes have received considerable attention in biomedical research. Herein, novel nickel(II) complex [Ni(II)(HL)2].2H2O was synthesized from newly synthesised ligand 2-((2-hydroxyethyl)amino)quinoline-3-carbaldehyde (H2L) through bidentate fashion of metal–ligand interaction. The complex was characterized using spectroscopic and physicochemical methods. The formation constant (KNi(II) = 2.36 × 107) of the complex was calculated spectroscopically and thermodynamic parameters (ΔG, ΔH and ΔS) were determined from it. In vitro antibacterial activity analysis of the newly synthesized complex exhibited mean inhibition zones ranging from medium to high (16.55 ± 1.03 mm, 16.69 ± 0.63 and 20.94 ± 2.01 mm) at 600 μg/mL against E. coli, S. aureus and P. aeruginosa, respectively. The complex also showed enhanced antioxidant activities compared with the corresponding free ligand. The energy band gap (1.183 eV) was calculated from the HOMO and LUMO of the most stable structure of the synthesized complex. The DFT calculated results and molecular docking analysis results showed good agreement with the experimental results. The complex showed pronounced biological activities than the free ligand. The in silico binding modes of the complex against E. Coli DNA Gyrase and S. aureus Dihydrofolate reductase (PDB: 2w9h) were found to be in excellent agreement with the in vitro biological studies.

Cyclopentadienyl and indenyl ruthenium(II) complexes containing diazafluorenone derivative ligands: Syntheses, characterization, antibacterial and cytotoxicity studies

We have successfully synthesized a series of eight versatile, half-sandwich ruthenium(II) cationic complexes [(Cp/Ind)Ru(к2(N∩N)L)(PPh3)]PF6 (1–8), where L represents a 4,5-diazafluorenone derivative ligand. These complexes were isolated as their hexafluorophosphate salts and subjected to thorough characterization using various spectroscopic techniques such as FT-IR, NMR, UV and Mass. Furthermore, single-crystal X-ray diffraction studies determined the molecular structures of representative complexes 1, 7, and 8. We screened the synthesized complexes and ligands in vitro to assess their potential antibacterial activity against three bacterial strains: the Gram-positive Staphylococcus aureus, the Gram-negative Escherichia coli and Klebsiella pneumoniae. Remarkably, all the compounds exhibited potent antibacterial activity against the tested organisms. In addition, we conducted a cell viability assessment to evaluate the cytotoxicity of the free ligands. The results indicated that the ligands did not demonstrate statistically significant cytotoxicity. However, it is noteworthy that complex 1 displayed more pronounced cytotoxic effects on the DL cell line, followed by complexes 3, 5, and 7.

Design, synthesis, characterization, spectral, chemical analysis, biological evaluation, and molecular docking studies of novel fatty Schiff base ligands and their nickel and mercury complexes

A novel two Fatty Schiff bases ligands of (N-(4-(dimethyl amino) benzylidene Dodecane, heptadecane) hydrazide and N-(4-(dimethyl amino) benzylidene) dodecane, heptadecan hydrazides and their complexes with Hg and Ni were synthesized and distinguish by1HNMR, FT-IR, spectroscopy, elemental analysis, X-ray Diffractions, thermal gravimetric analysis, and magnetic moments. In-vitro strains have been used to study their antibacterial properties. The ligands and their metal complexes have been evaluated physiologically by various bacterial and fungal strains. In the comparison of free ligands with their complexes. The latter were a more potent antibacterial agent and were more efficient against gram-positive bacteria than gram-negative bacteria. Additionally, investigations using molecular docking have been carried out to assess the ideal binding location and its inhibitory effect.

A two-fold interpenetrated mixed-ligands acentric 3D coordination polymer Zn(OBA)(DIB)·0.5H2O: Topological analysis, fluorescent and second-order NLO properties

Second-order nonlinear optical (NLO) materials have important applications in the realms of photoelectronics and photonics whose microstructures need to be organized into a noncentrosymmetric (NCS) structure. In this work, a mixed-ligands three-dimensional (3D) noncentrosymmetric coordination polymer Zn(OBA)(DIB)·0.5H2O (1) was hydrothermally prepared from 4, 4′-oxydibenzoic acid (H2OBA), 1, 3-di(1H-imidazol-1-yl)benzene (DIB) and Zn(NO3)2·6H2O via spontaneous resolution approach, which crystallizes in a noncentrosymmetric space group Fdd2. Compound 1 was characterized by powder X-ray diffraction (XRD), thermogravimetric (TGA) and IR analyses. The structural analysis shows that 1 is a two-fold self-interpenetrated three-dimensional (3D) network material. Single crystal X-ray diffraction and the topological analysis manifests that the topological structure of 1 belongs to a cds topological net. The measurement of the fluorescent properties of 1 and the free DIB ligand show that the emission peak at 460 nm of 1 can be attributed to the charge transition from the п bond electron to the п anti-bond orbital of the DIB ligand. The second-harmonic generation (SHG) measurement shows that the second-order NLO effect of compound 1 is approximately equivalent to that of potassium dihydrogen phosphate (KDP). Compound 1 is high thermal stable and insoluble in water and common organic solvents, making it to be a potential candidate as a second-order NLO material.

New thiosemicarbazones and their palladium(II) complexes: Synthesis, spectroscopic characterization, X-ray structure and anticancer evaluation

Thiosemicarbazones (TSCs) have proven to be an important group of NS donor Schiff base ligands. Their biological activities, structural and donor diversities are often improved after coordination to a metal ion. In this work, novel thiophene-based thiosemicarbazone ligands; (E)-N,N’-dimethyl-2-((5′-methyl-[2,2′-bithiophen]-5-yl)methylene)hydrazine-1-carbothioamide (L1), (E)-N-ethyl-2-((5-phenylthiophen-2-yl)methylene)hydrazine-1-carbothioamide (L2) and (E)-2-((5′methyl)-[2,2′-bithiophen]-5-yl)methylene)-N-phenylhydrazine-1-carbothioamide (L3) were synthesized via condensation reaction. The corresponding complexes (C1, C2 and C3) were synthesized by reacting the ligands with Pd(cod)Cl2 under inert nitrogen environment. All the prepared ligands and complexes were characterized by using the FTIR, UV–Vis, 1H and 13C NMR, elemental analysis and single crystal X-ray crystallography on ligand L2. The anticancer activities of the complexes were investigated against human the Caco-2, HT-29, HeLa and non-cancerous KMST-6 cell lines. In the preliminary studies, unexpectedly of all ligands and complexes, L1 showed the best anti-tumor activities at 100 µg/mL with cell viabilities < 31% in all the cell lines. In general, cell lines were more susceptible to complexes than free ligands except for C1. Complex C2 had the highest activity among complexes; HeLa (8.4%), HT-29 (8.8%), Caco-2 (16.1%) and KMST-6 (24.5%) cell viabilities at a concentration of 100 µg/mL. The C3 complex demonstrated appreciable selectivity since it had minimal effect on non-cancerous KMST-6 cell line (76%) with relatively reduced cytotoxicity in other cells except in HeLa (0.0%). All the complexes prepared inhibited proliferation of HeLa cells.

Column chromatography separation of lanthanide(III) bisphthalocyaninate and phthalocyanine ligand

During the synthesis of double-decker f-metal phthalocyanine complexes Ln(Pc)2 free phthalocyanine ligands can be also formed, however, routine column chromatography is not effective for their separation. The preliminary reduction of the complexes with hydrazine hydrate affords the low mobile forms, which can be re-oxidized in the chromatography columns after the free ligand is eluted.

Synthesis, characterization and structural study of two imidazole oxime ligand and their ZnII mononuclear coordination compounds

This paper presents a combined experimental and computational study of two new mononuclear Zinc(II) coordination compounds. The {Zn(MICO)2Cl2} (I) and{Zn(MIPMO)2Cl2} (II) complexes have been synthesized and characterized by NMR, UV, FTIR and single crystal X-ray diffraction techniques. The single crystal X-ray analyses reveal that the centrosymmetric ZnII cation in both complexes {Zn(MICO)2Cl2} (I) and {Zn(MIPMO)2Cl2} (II) is tetrahedrally coordinated by two chelating imidazole oxime ligands and by two chlorine atoms in a distorted tetrahedral geometry. The intremolecular interactions were found to play an important role in determining the most favorable structure of the free ligands, therefore controlling the final coordination mode. The cohesion of the structure and stability are ensured by intermolecular OH···O, OH···N, OH···Cl and CH···O hydrogen bonds. Hirshfeld surface analysis was performed to study the nature of intermolecular interactions within the crystal structure via 3D and 2D fingerprint surfaces and to demonstrate H-bonding with close contacts in crystal via dnorm surface. The stability of the prepared ZnII complexes has been evaluated through the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), and energy gap. The molecular geometries and electronic transitions of the two complexes and their ligands in the ground state have been calculated using the mPW1PW91 basis at the TZVP level of theory.

Triphenylphosphine Thiolate Gold(I) Complexes with Redox-Active Schiff Bases: Synthesis, Electrochemical Properties, and Biological Activity

New gold(I) phosphine thiolate complexes [(Ph3P)Au(SLn)] I–V with Schiff bases LnSH containingredox-active catechol, phenol, or quinone methide moieties were synthesized and characterized. Themolecular structure of compound I in the crystalline state was established by X-ray diffraction (CCDCno. 2237815). The electrochemical behavior of compounds I–V was studieв by cyclic voltammetry. The proposedelectrooxidation mechanism of the complexes involves the Au–S bond cleavage, the disulfide formation,as well as the oxidation of the redox active group of the ligand. In the cathode region, complexes I–IIItend to form relatively stable monoanionic species. The radical scavenging activity of complexes decreases incomparison to free ligands in the reactions with synthetic radicals and the CUPRAC test. Compounds I, II,IV, and V have no clear-cut effect on the promoted DNA damage; however, they show antioxidant actionin the non-enzymatic lipid peroxidation of rat liver homogenate. Compounds I–V demonstrate a weak antibacterialactivity against Staphylococcus aureus strains. The gold(I) complexes cytotoxicity was studied againstA-549, MCF-7, and HTC-116 cancer cell lines using MTT assay. The test compounds are characterized byhigher selectivity to certain types of cells than the sulfur-containing Schiff bases. The presence of quinonemethide moiety in the ligand in case of V significantly increases the cytotoxicity against all of the cell lines.

Novel 1,3‐diphenyl‐4‐(N,N‐dimethylimido dicarbonimidic diamide azo)‐5‐pyrazolone and its chelates with manganese, nickel, copper, and zinc divalent metal ions as an antibacterial activity supported by molecular docking studies: Design, synthesis, DFT, and TD‐DFT/PCM calculations

A novel 1,3‐diphenyl‐4‐(N,N‐dimethylimidodicarbonimidic diamide azo)‐5‐pyrazolone as a ligand, simplified as DNP, and its chelates were prepared. Characterization of the structures was performed based on several analytical and spectroscopic techniques. To support these studies, density functional theory (DFT) calculations were carried out by using the B3LYP level, B3LYP/6‐311G** level for the free ligand, and B3LYP/6‐311G**‐LANL2DZ functional level for the solid chelates. The acquired results indicated that DFT calculations generally give compatible results with the experimental ones. Hyper conjugative interactions, molecular stability, bond strength, and intramolecular charge transfer were examined by applying natural bond orbital (NBO) analysis. Nonlinear optical properties of the obtained compounds were investigated by determining molecular polarizability (α), and hyperpolarizability (β) parameters provided a hint for the synthesized compounds' intriguing optical characteristics. The electronic structure of the ligand and its complexes were predicted using the time‐dependent DFT (TD‐DFT) method with a polarizable continuum model (PCM) exploiting the B3LYP approach combined with a 6‐31G(d,p) basis set. The prepared compounds' antibacterial activity was experimentally verified utilizing the agar well diffusion method versus selected G + and G‐ bacteria. The molecular docking mechanism between the bacterially resistant chelates and their inhibited bacteria protein pocket receptors was carried out to determine the modes that these compounds bind to the protein's active sites.

Crystal Structures of DNA Intercalating Agents Dipyrido[3,2-f:2′,3′-h]quinoxaline (dpq), (Benzo[i]dipyrido[3,2-a:2′,3′c]phenazine (dppn), and [Ir(ppy)2(dppn)][PF6] (Where Hppy = 2-Phenylpyridine)

Pyrazino-phenanthroline ligands are commonly used with transition metals as DNA intercalation agents. Herein, we report the characterization of two commonly utilized pyrazino-phenanthroline ligands, dipyrido[3,2-f:2′,3′-h]quinoxaline (dpq) and (benzo[i]dipyrido[3,2-a:2′,3′c]phenazine (dppn), by single-crystal X-ray diffraction. Additionally, the characterization of [Ir(ppy)2(dppn)][PF6], where Hppy = 2-phenylpyridine, by single-crystal X-ray diffraction is described. Both the dpq and dppn ligands crystallize as chloroform solvates where the chloroform molecule occupies the equivalent binding pocket of a metal in metal complexes of these ligands. These pyrazino-phenanthrolines are largely planar, with the dppn ligand displaying a slight twist. When the dppn ligand is coordinated to iridium(III), the dppn ligand on the resulting complex displays a significant degree of bending along the longitudinal direction of the ligand. This iridium (III) complex crystallizes as a CH2Cl2 and Et2O solvate and due to the volatility of these solvents these crystals are only stable for a few seconds outside of the mother liquor. The structures of the free ligands and the [Ir(ppy)2(dppn)][PF6] complex all display extensive π stacking interactions.

AMP Aptamer Programs DNA Tile Cohesion without Canonical Base Pairing.

Tile-based DNA self-assembly provides a versatile approach for the construction of a wide range of nanostructures for various applications such as nanomedicine and advanced materials. The inter-tile interactions are primarily programmed by base pairing, particularly Watson-Crick base pairing. To further expand the tool box for DNA nanotechnology, herein, we have designed DNA tiles that contain both ligands and aptamers. Upon ligand-aptamer binding, tiles associate into geometrically well-defined nanostructures. This strategy has been demonstrated by the assembly of a series of DNA nanostructures, which have been thoroughly characterized by gel electrophoresis and atomic force microscopy. This new inter-tile cohesion could bring new potentials to DNA self-assembly in the future. For example, the addition of free ligand could modulate the nanostructure formation. In the case of biological ligands, DNA self-assembly could be related to the presence of certain ligands.

In silico, in vitro and docking exploration for some novel coordination complexes derived from bioactive indole moiety

The reaction of 5-methyl-3-phenyl-1H-indole-2-carbohydrazide with 4-methoxybenzaldehyde gave the new ligand molecule; N'-(4-methoxybenzylidene)-5-methyl-3-phenyl-1H-indole-2-carbohydrazide. The novel Cu(II), Co(II) and Zn(II) coordination complexes have been successfully prepared. The newly prepared ligand and its coordination complexes were characterized by analytical, FT-IR, 1H NMR, mass, UV-visible, molar conductivity, and magnetic susceptibility measurements. The spectral data reveal the octahedral geometry for all the metal (II) complexes. DFT estimations for the ligand at the DFT/B3LYP level via 6-31G++ (d, p) replicate the structure and geometry. Furthermore, molecular docking and ADME calculations were also performed to correlate and interpret the experimental results. The biological activity study illustrated enhancement in the activity of the free ligand containing bioactive indole moiety upon complex formation. The newly prepared Cu(II) and Zn(II) coordination complexes may be considered a promising antibacterial and antifungal agent. The Cu(II) and Zn(II) complexes showed MIC 12.5 µg mL−1 against E. coli, S. aureus and C. oxysporum. Also, the Zn(II) complex showed promising anti-TB activity against M. tuberculosis (MIC 3.125 µg mL−1). Further, the study extended to evaluate their in vitro antioxidant activity, and in silico docking study against Cytochrome c Peroxidase (PDB ID: 2 × 08), the Cu(II) complex showed excellent activity as compared to standard drug.